Download Lightning Room education kit: Classroom activities

Lightning Room School-based activities
School-based activities
Static electricity
Background information
You may be familiar with getting zapped while getting out of a car, or zapping yourself or
someone else after walking on carpet. These incidents involve static electricity. Static
electricity occurs when electric charge builds up in one place. When you rub two
different materials together, you can move negative charges (electrons) from one
material to the other. This is often referred to as ’charging up’ the materials. If the static
electricity is strong enough, you can see and/or hear a spark moving from one object to
another as it discharges. Discharging occurs when electrons move between a charged
object and an object that is connected to the ground (‘earthed’).
There are two types of charge, positive charge and negative charge.
• When two materials have the same charge (positive and positive or negative and
negative), they repel each other.
• When two objects have different charges (positive and negative or vice versa)
they attract each other.
• Charged objects attract neutral objects (objects that have no charge).
If an object is charged, it will discharge when it is in
contact with or close to the ground. This contact can be
either direct or indirect. For example, a charged rod will
discharge through the ground via the human body when
it comes into contact with a human finger. The charge is
given a pathway to the ground via the person's finger. A
strong charge can jump to the finger if it is close
enough. The person may feel a little shock as the rod
discharges.
Lightning is a discharge of static electricity on a much
larger scale. Buildings have lightning rods that reach
high into the sky so that the charged clouds can
discharge through them to the ground. This protects
buildings by providing a safe path for the electricity to
pass through.
The Triboelectric Series
Tribology is the study of friction. The triboelectric effect
is the transfer of charge between materials that are
rubbed together.
Materials lower on the list alongside will acquire a
negative charge when rubbed against materials higher
on the list.
Activities 1-4 relate to static electricity.
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The Triboelectric Series
+ Positive
Air
Human skin
Asbestos
Rabbit fur
Glass
Human hair
Nylon
Wool
Silk
Aluminium, zinc
Paper
Cotton
Steel
Wood
Hard rubber
Copper, nickel, carbon
Brass, silver
Gold, platinum
Polyester
Polyurethane
Polyethylene
PVC (vinyl)
Teflon
─ Negative
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Lightning Room School-based activities
Activity 1: Static experiences
What to do
List your daily encounters with static electricity. For example:
• pulling clothes out of the dryer
• touching door handles in a carpeted room
• getting out of the car
• taking off certain clothes
• emptying rice out of its plastic bag.
Search the Internet for more examples of static electricity
(e.g. Science Made Simple: http://www.sciencemadesimple.com/static.html )
Compare your findings in small-group discussion.
Activity 2: Hundreds and thousands
What you need
• ‘hundreds and thousands’
• shallow (l or 2 cm) container with a clear plastic lid
(e.g. a small take away food container)
• woollen clothing or cloth.
What to do
1. Put a small amount of ‘hundreds and thousands’ in the container.
2. Put the lid on the container and charge the lid by rubbing it with a woollen cloth.
Observe what happens.
3. Gently move a finger over the top of the container and observe what happens.
Questions
1. Why do the ‘hundreds and thousands’ often jump back down?
2. What happens when you move your finger over the top of the container?
Shallow container with clear plastic lid
‘Hundreds and thousands’
Neutral spheres are attracted to the lid and
the charged ones are repelled
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Lightning Room School-based activities
Activity 3: Boat races
What you need
• corks
• plastic pens
• woollen cloth or clothing
• large bowl of water.
What to do
Static electricity can be used to play a simple boat-race game.
1. Each player floats a cork ‘boat’ in the large bowl of water.
2. The boats are pushed under water so they come up wet.
3. Each player then charges up a plastic pen by quickly rubbing it on the woollen
cloth or clothing.
4. Players then use their pens to pull the boats from one side of the bowl to the
other by placing the pen close to the wet cork (being careful not to touch the cork
or the water). The first cork/boat to touch the other side of the bowl wins.
If the pen touches the wet boat or the surface of the water, the pen will discharge and
the boat will stop. The students may need to charge their pens more than once during
the race.
Activity 4: Shocking facts about lightning
What you need
Access to encyclopedias and other reference books, or to the Internet.
(e.g. US National Weather Service: http://www.lightningsafety.noaa.gov/index.htm )
What to do
1. Find out some amazing facts about lightning. For example:
• How long is a lightning bolt?
• Can lightning’s energy be caught and stored?
• Big buildings get hit by lightning all the time. Why don’t they burn down?
• How many people are killed by lightning per year?
• What can you do to prevent yourself from being struck by lightning?
• Some people have been hit by lightning many times. Why have they
survived?
• How many bushfires are started by lightning strikes?
• ‘Lightning never strikes twice in the same place.’ Is this a myth or a fact?
2. Present the results of your research. For example:
• Download lightning images from the Internet and project them to illustrate a class
presentation on ‘Shocking facts about lightning’.
• Write a fictional story using one or several of the amazing facts about lightning
that you have discovered.
• Write a poem or song that explains how to avoid being struck by lightning.
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Lightning Room School-based activities
Cells and batteries
Background information
A cell is a single device that changes chemical energy into electrical energy. A torch
battery is actually a cell (in scientific terms). A battery is a number of cells connected
together in a particular way (in series). A car battery is made up of at least six cells.
When a cell or battery is connected to a conductor, one end becomes the positive
terminal and the other end becomes the negative terminal. To connect one cell in series
with another cell, the positive terminal of one cell should be connected to the negative
terminal of the next cell. Connecting cells together in series increases the voltage
available.
In 1800, Volta made the first battery using the principle that two different metals
connected by certain liquids produce electricity.
A simple low-powered cell can be made using a lemon and two different metals. If you
wanted to make a 'battery' using lemons, one lemon would need to be connected to
another lemon with wires connecting alternate metals.
Alessandro Volta
http://www.chemistryexplained.com/
Activities 5-7 relate to cells and batteries.
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Lightning Room School-based activities
Activity 5: Lemon battery
What you need
• lemons
• small pieces of zinc
• small pieces of copper
• wires
•
•
a voltmeter or multi-meter
(switched to volt)
small light globe.
What to do
1. Give a lemon a good squeeze, but be careful not to split the skin.
2. Connect a wire to a piece of zinc and push the metal into the lemon.
3. Connect another wire to a piece of copper and push the metal into the lemon.
4. Connect the wires to the voltmeter (see diagram).
5. Record the voltage created by the lemon cell.
6. Connect a light globe into the circuit in place of the voltmeter and record what
happens.
7. You may find that the current is too small to light a light globe. Connect a number
of lemons together as shown in the diagram until the current is large enough to
light the light globe. Record your results.
Questions
1. Is the voltage supplied by one lemon enough to light the light globe?
2. How many lemons did it take to light the light globe?
3. If you assume that each lemon supplies the same voltage, calculate the voltage
that was required to make the light globe light up.
4. Describe the energy transformations taking place in this circuit.
Optional
Experiment with other substances in place of the lemons such as vinegar, potatoes,
cola or a cactus.
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Lightning Room School-based activities
Activity 6: Voltaic piles
What you need
• aluminium foil
• metal washers
• paper
• salt water
• voltmeter
• wires
•
•
10 cent and 2 cent coins
(available from coin shops, or use
similar copper disks)
other materials such as copper, zinc
What to do
1. Make a voltaic pile, (see
diagram), with paper dipped
in salt water sandwiched
between aluminium foil and a
washer.
2. Measure the voltage between
the two metals with a
voltmeter and record this
value.
3. Try multiple layers, (see
diagram). Set up a suitable
table on your computer and
record the voltage each time.
4. Try other combinations of
metals, each time measuring
the voltage with the voltmeter.
Record the results in your
table.
Questions
1. Did you construct a single cell or a battery in each trial? Explain your answer.
2. Which combination gave the greatest voltage reading?
3. Describe the energy transformations taking place in this circuit.
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Lightning Room School-based activities
Activity 7: Battery (cell) life
What you need
• voltmeter
• wires
• light globe
• clock/watch
• several types of cells (for example, cheap and expensive carbon cells,
rechargeable Nicad cells, alkaline cells). They all need to be the same size, for
example, D cells. Note the purchase price of each.
What to do
1. Set up the circuit shown in the diagram.
2. Take the voltage reading across the cell every two minutes and record the results
in a table that you set up on your computer.
3. As the cell goes flat and the light grows dimmer, note the voltage at which you
would consider the cell to be of little further use.
4. Mark this point on a voltage versus time graph for this cell.
5. Repeat for the other cells. If you want to conduct a shorter experiment, choose
smaller cells such as AA.
Questions
1. Which cell lasted longest?
2. Which cell(s) died with very little warning?
3. For each cell, work out:
time lasted (minutes)
cost (cents)
4. Which gave the best value for money?
voltmeter
1.5V D cell
light globe
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Lightning Room School-based activities
Electric circuits
Background information
Moving charge is called current. Conductors are materials that allow current to
flow easily through them. Metals, for example, are good conductors of electricity.
Insulators are materials that don't allow current to flow through them easily. Examples of
insulators are wood, glass and plastic.
When an ammeter (an instrument that measures current) is connected in a circuit with a
cell or battery, a light globe and a good conductor, the light globe will light up and the
ammeter needle will move. Poor conductors will allow electricity to pass through them
and will make the ammeter needle move but will not light the light globe. Insulators will
not allow electricity to pass through them so the light globe will not light up, nor will the
ammeter needle move.
When a battery or cell is connected in a circuit, it produces a current that travels in one
direction only. A current that flows in one direction only is called direct current or DC
current. The current that comes to your home is called alternating current or AC current.
This type of current is produced by generators. AC current changes direction many times
in one second. The current that comes to your home alternates back and forth 50 times
in one second (50Hz). Some appliances have special electronic devices in them to
convert the AC current to DC current.
Electrical appliances convert electrical energy into other forms of energy such as
movement and sound (kinetic energy), heat (thermal energy) light and stored energy
(potential energy). The energy in food and batteries is called chemical potential energy.
There are other types of potential energy.The energy of compressed springs and drawn
archery bows is mechanical potential energy. Examples of objects that have gained
gravitational potential energy are lifts that have moved up and boxes raised by forklift
trucks.
Ammeter
http://www.ngfl-cymru.org.uk/vtc/ngfl/
science/107/PP-electricity.html
Activities 8-10 relate to electric circuits.
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Lightning Room School-based activities
Activity 8: Conductors and insulators
What you need
• Conductor worksheet (one copy per group or individual, see next page)
• 1.5 V cell (’battery’)
• small light globe
• four lengths of insulated wire
• a collection of objects such as a fork, copper wire, aluminium foil, plastic object,
dish of water, dish of salty water, graphite pencil (with both ends sharpened),
piece of wood, chalk, keys, silver rings, gold rings
• an ammeter (if available)
Primary teachers: Your neighbours may have a multi-meter which can act as an
ammeter. Alternatively, your local secondary school is likely to have an ammeter
that you can borrow.
What to do
1. Construct an electrical circuit as shown in the diagram below.
2. Test the circuit by connecting a piece of wire between A and B. The light globe
should light up.
3. Explore a range of objects and materials to see which act as good conductors
between A and B and light the light globe.
4. Complete the Conductor worksheet that can be found on the next page.
Questions
1. Which objects or materials caused the light globe to light up?
2. Are these materials good conductors or poor conductors?
3. Which objects or materials caused the needle on the ammeter to move but did
not cause the light globe to light up?
4. Are these materials good conductors or poor conductors?
5. Which objects or substances didn’t affect the needle on the ammeter or light up
the light globe?
6. What are these materials called?
Material to be tested is placed
between A and B
1.5V cell
A
ammeter
B
light globe
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Lightning Room School-based activities
Conductor Worksheet
Object tested
Made of?
Ammeter reading
(Amps)
Light globe
Not lit
Example:
Conducting wire
Copper
1.4
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Dimly lit
Conclusion
Brightly lit
Yes
Conducting wire is a good
conductor.
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Lightning Room School-based activities
Activity 9: Switches and circuits
What you need
• cell (battery)
• tape
• three pieces of insulated wire
• light globe
• two drawing pins
• small piece of cork
• paper clip.
What to do
1. Try to use one cell and one wire to make the light globe light up. Is this possible?
2. Use one light globe, one cell and two wires to make the light globe light up.
3. Make a switch as shown in the diagram below. By pressing the paper clip down,
the circuit will be complete and the light globe will light up.
Questions
1. Were you able to light up the light globe using only one cell and one wire? Try to
explain why/why not.
2. Describe the energy transformations that took place in the circuit you constructed
in Step 2.
3. Why do you think switches are useful in electric circuits?
Further research
Search the Internet for websites describing ‘electrical circuits’,
e.g. http://science.howstuffworks.com/circuit.htm.
Summarise the additional information about circuits that you find.
Present your summary to your class as a short report.
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Lightning Room School-based activities
Activity 10: Electrical safety
What you need
• Internet access or other research facilities
• poster paper
• graph paper
• volunteers
• multiple copies of the Electrical safety worksheet (see next page).
What to do
1. Answer the questions on the Electrical safety worksheet to find out how much
you know about electrical safety.
2. Do some research on electrical safety and investigate common misconceptions
about electrical safety.
3. Make a poster demonstrating what to do and what not to do when using electrical
appliances. Alternatively, use computer software such as PowerPoint to make a
short presentation on electrical safety.
Optional
4. Survey ten people you know using the Electrical safety worksheet and graph the
findings.
5. Survey classmates or other year levels using the Electrical safety worksheet to
compare different age groups.
Answers to the Electrical safety worksheet
1F
6T
11F
2T
7F
12T
3T
8T
13F
4T
9T
14T
5F
10F
15F
http://museumvictoria.com.au/scienceworks/Education/
http://www.labelsourceonline.co.uk
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Lightning Room School-based activities
Electrical safety worksheet
Are you switched on to electrical safety?
Read each statement carefully and decide if it is true or false.
Write T or F in the box.
1.
Any tradesperson listed in the telephone book is qualified to do electrical
work in your home.
2.
If you are outside playing in a thunderstorm the best thing to do is to go
indoors.
3.
Using double adaptors increases the risk of overheating and fire.
4.
You should not use the telephone during a thunderstorm.
5.
All houses in Victoria have a safety switch in their switchboard.
6.
You should always wear shoes when you use the washing machine.
7.
It is safe to fly a kite near power lines.
8.
The human body can conduct electricity.
9.
If a power line is broken and has fallen down you should stay at least six
metres away.
10.
When working outside with electrical appliances you should wear thongs.
11.
If an electric cord is frayed, the best thing to do is to wrap electrical tape
around it.
12.
All electrical appliances should be switched off and unplugged when not in
use.
13.
If someone gets an electric shock you should move them to a safe position.
14.
If an appliance is faulty you should have it fixed or destroy it.
15.
Babies are too small to get hurt if they poke things into a power point.
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Lightning Room School-based activities
Electricity and magnetism
Background information
Hans Christian Oersted discovered that electric currents produce magnetic fields. He
noticed that a magnetic compass needle moved when it was placed near a wire carrying
current. This suggested that when the wire carried a current, it had a magnetic field just
like ordinary magnets. When the current was switched off, the wire stopped being a
magnet.
Magnets that you are familiar with are generally magnetic all the time. By winding wire
around particular metals and passing a current through the wire, we can make a stronger
electromagnet. Big electromagnets are used to move scrap iron in junk yards – the
electromagnet is switched on to pick up the metal scrap and switched off to drop it.
The power supply in Australia brings AC current to every household. The frequency of
the household power supply in Australia is 50 Hertz. This means that the current goes
forwards and backwards 50 times each second. If you brought a magnet close to a light
globe that was switched on, the filament would vibrate. This is because the magnetic
field around the magnet and the magnetic field produced by the current-carrying wire
interact, causing a force to be exerted on the filament. The direction of the force will
depend on the direction of the current. Since the current is moving back and forth many
times a second, the filament is seen to vibrate.
The discovery of electromagnetism led Michael Faraday to discover the principle behind
the electric motor – when a coil of current-carrying wire is placed between magnets, the
coil turns. The motor can be made to rotate faster by increasing the number of coils
between the magnets, increasing the current in the wire or using stronger magnets.
Michael Faraday
http://commons.wikimedia.org/
Activities 11 & 12 relate to electromagnets and electric motors.
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Lightning Room School-based activities
Activity 11: A simple electromagnet
What you need
• Electromagnet worksheet (one per student or group, see next page)
• large nail or bolt
• long piece of insulated wire
• 1.5V cells (batteries)
• a packet of paper clips.
What to do
1. Strip the insulation from each end of the wire and twist the strands together.
2. Wind the wire around the nail about 15 times.
3. Connect the two ends of the wire to opposite ends of the cell.
4. Hold the nail close to a small pile of paper clips.
5. Count how many paper clips were picked up and record the number in the table
on the Electromagnet worksheet.
6. Repeat steps 2-5, changing the number of coils of wire wrapped around the nail.
Use the worksheet to record the number of paper clips picked up by the
electromagnet each time.
7. Try connecting two cells in the circuit and repeat steps 2-6. Record your results
on the worksheet.
8. Answer the questions on the worksheet.
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Lightning Room School-based activities
Electromagnet worksheet
Record the number of paper clips lifted in each column.
Number of winds of wire
15
20
25
30
1
Number of
cells
2
Questions
1. How many paper clips can be picked up using 15 coils and one cell?
2. How many paper clips were picked up using 25 coils and two cells?
3. Did connecting more cells in the circuit affect the number of paper clips
that were picked up?
4. What affects the number of paper clips that can be picked up?
Optional
Experiment with additional combinations of the number of cells and the number of coils.
Use a spreadsheet to record and graph the results of your research.
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Lightning Room School-based activities
Activity 12: Vibrating light globes
What you need
• strong magnet
• clear 240V incandescent household light globe connected to the mains power
supply (for example, a table lamp with the shade removed). Use a low wattage
light globe to avoid eye damage.
What to do
1. Bring the magnet near a light globe that is not switched on and record
observations.
2. Now bring the magnet near the light globe when it is switched on and record
observations.
Questions
1. Is the filament a magnetic material? Explain.
2. Why do you think the filament vibrated?
3. Your observations are based on what happens when you put a magnet near a
filament using AC current. What do you think the filament would do if the current
through it only moved in one direction (using DC current)?
It is very important that magnets not be brought close to computer screens or
televisions as this can permanently affect the screen image.
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Lightning Room School-based activities
Generators
Background information
Michael Faraday was the first person to make an electric generator. He understood that
many electrical effects are reversible. A simple electric generator is just a simple electric
motor in reverse. Generators convert movement into electricity when turbines turn coils
of wire between magnets, while electric motors convert electricity into movement by
using electricity to turn coils of wire between magnets.
Power stations have large turbines that are used to turn a magnet inside a big coil of
wire to produce electricity that eventually reaches your home. There are different types
of power stations. Many turn turbines using steam produced by burning coal, while
others use steam produced by nuclear energy. Some are more environmentally friendly
and use wind or water to turn their turbines.
Activities 13 & 14 relate to generators.
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Lightning Room School-based activities
Activity 13: Do-it-yourself generator
What you need
• solenoid (wire coil)
• iron bars to place in the solenoid
(e.g. uprights can be unscrewed from retort stands)
• bar magnets
• wires
• galvanometer.
What to do
1. Connect the solenoid to the galvanometer.
2. Set up a table on your computer to record your observations.
The table should have two columns:
Column 1 should be headed ‘Experiment’ and used to record what you did in
steps 3-8 below,
Column 2 should be headed ‘Observations’.
3. Move the north end of the magnet in and out of the solenoid (more than once)
and record your observations.
4. Move the south end of the magnet in and out of the solenoid (more than once)
and record your observations.
5. Move the magnet back and forth around the solenoid and record your
observations.
6. Insert an iron bar inside the solenoid and see what effect this has on the current
reading. Record your observations.
7. If you can alter the number of coils in the solenoid, increase the number of coils.
Repeat steps 1 to 5 and record the differences observed.
Questions
1. Was a current registered on the galvanometer when the magnet was not
moving?
2. Did the direction or reading of the current change when the magnet was inserted
and then removed? Explain.
3. Did the speed of the magnet’s movement affect the current?
4. Was there a difference in the current reading or direction when the magnet was
inserted the other way around (with the south end entering the solenoid first)?
5. Does placing an iron bar in the coil have any effect?
6. Does increasing the number of coils affect the direction of the current or the
current reading on the galvanometer?
solenoid
moving magnet
galvanometer
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Lightning Room School-based activities
Activity 14: Power to the people
What you need
• recording materials.
What to do
Brainstorm where mains electricity comes from. This will give an indication of students’
level of understanding.
Class discussion points
• In coal-powered power stations the generators convert the energy of coal into
electrical energy.
• It is easier to transport electricity rather than coal, thus the power station is close
to the coal supply.
• Is electricity a clean source of power? Consider living next to the power station.
• In Victoria, about half of the energy from brown coal is lost as heat. One quarter
is used to dry the brown coal itself. One quarter is turned into electrical energy.
• The energy from coal produces pressurised steam, which turns a generator.
What other sources of energy can be used to produce steam to turn a generator?
• What sources of energy can be used to turn a generator, without needing to first
burn a fuel to produce steam?
• Which source of power can produce electricity without burning a fossil fuel, and
without the use of an electrical generator?
Further research
Most power stations currently use the following four steps to produce electricity:
1. Fuel is used to heat water and produce pressurised steam.
2. Steam or other energy source turns turbines.
3. Turbines power the generators.
4. Electricity is produced and transmitted to consumers.
Some power stations use all four steps above, some can avoid step 1, and some can
avoid steps 1-3.
Search the Internet (‘power stations’ and ‘alternative energy sources’) to find out how
each of the power stations listed below works, and to find out which steps (1-4) are
needed for them to produce electricity.
•
•
•
•
•
Coal-fired
Gas-fired
Nuclear power
Hydro power
Geothermal power
•
•
•
•
Wind-powered
Wave-powered
Tidal
Solar power.
Why is it important to avoid step 1 if possible? What by-products and problems does this
step create?
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Lightning Room School-based activities
Activity 15: Developments in electricity
What you need
• brief biographies of famous people associated with electricity (following pages)
• research facilities.
What to do
1. Construct a ‘developments in electricity’ time-line using the biographies in the
following pages.
2. Use the Internet to research one of the following people in detail and prepare a
report on them:
• Thomas Edison
• Nikola Tesla
• Alessandro Volta
• Michael Faraday
• Benjamin Franklin
• Hertha Ayrton.
Include the following information:
When did the person live?
What were their main contributions to our knowledge of electricity?
Were any units of measurement named after them?
What was life like in their day and what effect did their discovery have on
people’s daily lives?
Search the Internet for relevant images and include these in your report.
Use Powerpoint or a poster format to produce a short class presentation
on the person you have researched.
Benjamin Franklin's experiment proving the identity of lightning
and electricity
http://original.britannica.com
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Lightning Room School-based activities
Biographies
Namarrkon
The Aborigines of northern Australia have a number of stories that explain thunder,
lightning and the wet-season clouds and rain. Namarrkon (spelling varies as the
consonant sounds have no exact equivalents in English) is the Lightning Spirit of the
Kunwinjku people of Western Arnhem Land in the Northern Territory. He/she has a circle
of flashing lightning leading from his/her head to the lower parts of his/her body.
Namarrkon creates electrical storms and destroys trees by throwing the stone axes that
protrude from his/her knees and elbows. It is widely believed that the marrkidjbu or
‘clever men’ have the power to call on Namarrkon to strike a particular person whom
they wish to have killed.
Thor
Thor was the god of thunder in Norse (Northern European) mythology. He had a magic
hammer which he threw with the aid of iron gloves. It always returned to him. Lightning
strikes occurred when his hammer hit something hard. Thunder was the sound of his
rolling chariot. Thor was the eldest son of Odin, the ruler of all gods. Thursday is named
after Thor.
Thales (about 580 B.C.)
Thales was born in Miletus in Asia Minor. He is considered to be the founder of Greek
philosophy and was one of the so called Seven Sages (Wise Men) of Greece. He
explained many natural phenomena.
Thales found that a piece of amber (fossilised plant sap), when rubbed with a cloth,
attracted feathers and the dried pith of plants. (The Greek word for amber is hlektron).
William Gilbert (1544–1603)
William Gilbert was an English physicist and physician who was educated at the
University of Cambridge. He was appointed physician to Queen Elizabeth I.
William Gilbert determined that a compass needle points north because the Earth
behaves as a giant magnet. In 1600 he published a book, De Magnete, which gave a full
account of all his experiments on magnets and electrical attractions. His book was used
as the main reference on electricity and magnetism for over 150 years.
Benjamin Franklin (1706–1790)
Benjamin Franklin was an American printer, author, diplomat and philosopher as well as
a scientist. In 1752 Franklin performed his famous experiment, which involved flying a kit
in a thinderstorm. The kite was used to ‘capture’ lightning, using a special storage device
called a Leyden Jar. The jar was connected to the kite by a string. His experiments were
the first to show that lightning is electricity. He was very lucky not to have been killed!
Franklin also explained how objects become charged and discharged using his theory of
‘positive’ and ‘negative’ charge.
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Lightning Room School-based activities
Petrus van Musschenbroek (1692–1761)
The Dutch physicist, Petrus van Musschenbroek is one of two people credited with the
invention of the Leyden Jar in about 1745. The German scientist, Ewald George von
Kleist, who was working independently, is also accorded this honour.
Leyden Jars were used to store static electricity. Van Musschenbroek’s jar was a waterfilled glass jar with an iron rod in it. It was named in honour of the city of Leyden, where
its inventor was born.
Ewald George von Kleist (1700–1748)
Ewald George von Kleist was the Dean of Kamin Cathedral in Pomerania (now a part of
Poland). Von Kleist discovered the Leyden Jar independently of van Musschenbroek.
His model used a chain in a glass jar, while van Musschenbroek’s used an iron rod.
Otto von Guericke (1602–1686)
Otto von Guericke was a German physicist who studied law and mathematics. Von
Guericke developed the first machine for producing an electrical charge. It consisted of a
sulphur ball which could be spun on an axle. The turning ball would be brushed with a
hand, a soft leather pad or a woollen cloth. Its operation was accompanied by showers
of sparks. Von Guericke also did many experiments on air pressure, including the
famous Magdeburg hemispheres demonstration, and invented the first air pump.
Luigi Galvani (1737–1798)
Luigi Galvani was an Italian professor of anatomy. Galvani accidentally discovered that
he could make a frog’s leg twitch violently when it was touched in different places by iron
and copper rods. He (wrongly) thought that the frogs leg contained ‘animal electricity’
that was released when it was touched by these metals. It was Volta who proved that the
frog’s leg and the two different metals were behaving like a battery. The electrical terms,
GALVANISM and GALVANISATION, were named in Galvani’s honour.
Allesandro Volta (1745–1827)
Alessandro Volta was an Italian physicist who performed many experiments with
electricity, and developed the first battery, called a Voltaic Pile. It consisted of stacked
copper and zinc plates, separated by paper or cloth that had been soaked in salt water.
Voltaic piles were the first steady source of electric current. In honour of his work,
Napoleon made Volta a count, and the electrical unit the VOLT was named after him.
Hans Christian Oersted (1777–1851)
Hans Christian Oersted was a Danish physicist who was educated at the University of
Copenhagen. In 1818, Oersted discovered that a magnetic compass needle will move
when it is placed near a wire carrying a current. He also discovered the first
electromagnet. This discovery began the study of electromagnetism, an important step
on the path to the first electric motor. Oersted was the first person to extract the metal
aluminium, and the magnetic unit, the OERSTED, is named in his honour.
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Lightning Room School-based activities
André Ampère (1775–1836)
André Ampère was a child prodigy who mastered every aspect of mathematics by the
time he was twelve. He went on to become a professor of physics, chemistry and
mathematics at various universities in France. Ampère built the first meter for measuring
electricity, and was the first person to work out the mathematical relationship between
electricity and magnetism. The unit of measurement of electric current, the AMPERE, is
named in his honour.
Michael Faraday (1791–1867)
Michael Faraday was the son of an English blacksmith and received little formal
education. He became a physicist and chemist, and is best known for his discoveries of
electromagnetic induction and electrolysis. In 1821, Faraday discovered the principle
behind electric motors, which convert electricity into movement. He understood that
many electrical effects are reversible – he was the first person to make an electrical
generator, which converts movement into electricity. The electrical unit, the FARAD, was
named in his honour.
Thomas Edison (1847–1931)
Thomas Edison developed the electric light bulb, the electric generator, the phonograph
and the motion picture. Altogether, Edison patented more than 1000 inventions. In 1882,
he developed and installed the world’s first large central electric power station in New
York City. This generator supplied direct current, while later generators produced
alternating current, as proposed by Nikola Tesla and George Westinghouse.
Nikola Tesla (1856–1943)
Nikola Tesla, an electrical engineer and inventor, was born in Smiljan (in the former
Yugoslavia). He emigrated to the United States in 1884 and later became an American
citizen. In 1888, Tesla developed the first system for generating alternating current.
George Westinghouse installed this system in the Niagara Falls power station, which
opened in 1895. In 1891, Tesla developed a high voltage transformer – the Tesla coil –
which has important applications in the field of radio communications.
The magnetic unit, the TESLA, is named in his honour.
Hertha Ayrton (1854–1923)
Hertha Ayrton was born in England. She was trained as a
mathematics teacher, but went on to become an electrical
engineer. Ayrton worked on the development of electric arc
lamps. Her inventions were used as searchlights during
World War I and in the cinema. Ayrton published many
papers on electric lighting, and was the first woman to
become a full member of the Institute of Electrical Engineers.
She was refused membership of the Royal Society on the
grounds that she was a married woman.
Hertha Ayrton
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